I'm having some problems w/ PMS and Ubuntu. I just set up a dual boot with XP and UB, and prior to running PMS on UB I installed mplayer according to this post.

Everything seems to be ok because I can play the files in UB just fine using mplayer and movies I have watched before with windows&PMS now wont work. MKV files say they are corrupted and regular AVI's that the PS3 should support natively say they are not supported.

lternatively go to Synaptic and ensure that the following are installed: mplayer, vlc, FFMPEG, and mencoder. Install all and everything should be funky

EDIT: I should add that I set this up yesterday under Kubuntu 9.04 and had problems playing back divx files until I installed FFMPEG. I would also advise downloading the static version of tsmuxer from the Smartlabs website and placing it into the tsmuxer folder(under the pms folder) as I noticed I had a load of errors in the Trace Log until I replaced it.